Please cite this article in press as: G.D. Yadav, P.A. Chandan, A green process for glycerol valorization to glycerol carbonate over heterogeneous hydrotalcite catalyst, Catal. Today (2014), http://dx.doi.org/10.1016/j.cattod.2014.01.043 ARTICLE IN PRESS G Model CATTOD-8891; No. of Pages 7 Catalysis Today xxx (2014) xxx–xxx Contents lists available at ScienceDirect Catalysis Today j our na l ho me page: www.elsevier.com/locate/cattod A green process for glycerol valorization to glycerol carbonate over heterogeneous hydrotalcite catalyst Ganapati D. Yadav ∗ , Payal A. Chandan Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400019, Maharashtra, India a r t i c l e i n f o Article history: Received 15 November 2013 Received in revised form 13 January 2014 Accepted 27 January 2014 Available online xxx Keywords: Bioglycerol Calcined hydrotalcite Green chemistry Glycerol carbonate Kinetics a b s t r a c t Biodiesel production is accompanied by 10% w/w glycerol which needs to be valorized to into bulk and specialty chemicals in order to make the biodiesel economics favorable. Glycerol carbonate is one such product from glycerol which has many potential applications. A green process using calcined hydrotalcite supported on hexagonal silica (CHT-HMS) catalyst was developed for the conversion of glycerol to glycerol carbonate using dimethyl carbonate. Effects of various Al:Mg composition and loading on hexagonal mesoporous silica (HMS) were studied. Al:Mg composition of 1:2 with 15% w/w loading on HMS was the best catalyst. . CHT-HMS catalyst was fully characterized by various techniques such as FT-IR, EDAX, SEM, TPD, XRD, etc. The effects of various parameters such as speed of agitation, catalyst concentration, mole ratio, and temperature were studied. The catalyst is robust and recyclable. The reaction follows Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism with weak adsoption of all species. Thus, a second order rate equation for the reaction was developed and the activation energy estimated. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Biodiesel production is accompanied by 10% w/w glycerol as a co-product which needs to be utilized in order to make the eco- nomics favorable [1–6]. The use of bio-diesel is considered as the green alternative to reduce carbon emissions. Additionally, the needs of new economic synthetic routes for chemicals starting from non-petrochemical sources are desirable and therefore glyc- erol would be acceptable as a raw material. In 2011, 66.2% of the total glycerol was produced from bio-diesel industry. US consump- tion of biodiesel rose from 263 million gallons in 2010 to 878 million gallons in 2011 to 1 billion gallon in 2012, demand for biodiesel fell and so did prices. The EPA has mandated the use of 1.28 billion gal- lons of biodiesel in 2013. Production came from 112 biodiesel plants with capacity of 2.2 billion gallons per year. Increasing biodiesel demand will continue to supply glycerol abundantly and it needs to be valorized [10]. Several bulk and specialty chemicals could be produced with glycerol as platform [7–9]. Conversion of glycerol to glycerol car- bonate is one of the attractive options to valorize glycerol. Glycerol carbonate is a fairly new chemical in the market, which possibly will present some new commercial applications [10]. ∗ Corresponding author. Tel.: +91 3361 1001/1111/2222; fax: +91 3361 1002/1020. E-mail addresses: gd.yadav@ictmumbai.edu.in, gdyadav@yahoo.com (G.D. Yadav). Glycerol carbonate is an attractive starting material due to the presence of two competing sites of reactivity in it. Glycerol monoesters, glycerol carbonate esters, glycerol monourethanes, glycerol diurethanes, are obtained from glycidol or glycerol car- bonate which are non-ionic glycerilic oxygenated surfactants, and non-ionic glycerilic oxygenated and nitrogenated surfactants [10]. Glycerol carbonate is an intermediate in the alkylene carbonate family with many potential areas of application such as reactive protic solvent and solvent for battery electrolyte, filming lubricants, agrosynthons, filming plasticizers, CO 2 separation from gaseous mixtures, phenolic resin preparation, synthesis of new function- alized polymers like polycarbonates and polyurethanes, medicinal and sanitary field, wetting agent ingredient for cosmetics, polymer bases for emulsions; as a surfactant component in coating and paint industry; and a substitute for ethylene carbonate and propylene carbonate, etc. [11]. The production of organic carbonates is cur- rently 80,000 TPA and carbonate based polymers 1.1 MTPA, which is expanding continuously. The production will continue to grow, especially if their use as additives for fuels expands [7]. Enzymatic synthesis of glycerol carbonate from glycerol and dimethyl carbonate was reported with 74% conversion of glycerol and 80.3% selectivity towards glycerol carbonate [12]. Sulfur assisted carbonylation of glycerol with carbon monoxide has also been studied [13]. A few reports deal with synthesis of glycerol carbonate from glycerol and urea with liberation of ammonia gas over gold [14], lanthanum oxide [15] and hydrotalcite catalyst [16]. Urea has been used as a reagent to make glycerol carbonate with lanthanum oxide as solid base catalyst [17] and zinc containing homogeneous catalysts [18]. However, the use of urea suffers 0920-5861/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cattod.2014.01.043